Self-adhesive electronic circuit

ABSTRACT

An electronic circuit including a planar base having first and second base surfaces, an antenna attached on the first surface of the base, and a chip connected to the antenna, characterized in that a double faced adhesive is glued on one of the base surfaces, the double faced adhesive having an opening and the chip being arranged at least partially in the opening.

FIELD OF THE INVENTION

The present invention relates to the attaching of electronic circuits.

DISCUSSION OF RELATED ART

Labels bearing indications readable by a computer peripheral, like a barcode readable by an optical analyzer, have recently appeared. Such asystem enables fast identification of a labeled product. For a label tobe read, it has to be in front of the analyzer, which implies a handlingof the product, the label of which is desired to be read. Finally, theinformation contained in the bar code cannot be modified.

An electronic label including an antenna connected to a chip enables, bymeans of an electromagnetic antenna coupled to a computer system,reading and writing information in the chip. It is not necessary to havethe electronic label face the antenna for the information exchange to bepossible. This type of label has many advantages, since a large amountof immediately rewritable information can be stored therein, withouthaving to handle the object, the label of which is being read. However,conventional electronic devices including a chip generally are toostiff, too thick and too expensive to enable making a robust,inexpensive electronic label of small bulk. Further, attaching the labelto the object always is a problem.

SUMMARY OF THE INVENTION

The present invention enables producing in a simple way and with a lowcost thin flexible self-adhesive electronic labels which are easy tolay, by machine or by hand.

To achieve this object, the present invention provides an electroniccircuit including a planar base, an antenna attached on a first surfaceof the base, a chip connected to the antenna and a double faced adhesiveglued on one of the base surfaces, a slot being made in the double facedadhesive and the chip being arranged at least partially in this slot.

According to an embodiment of the present invention, the chip is gluedon the first surface of the base and is connected to the antenna byconnection wires, the wires and the chip being covered with a drop ofresin.

According to an embodiment of the present invention, the etched surfaceof the chip faces the first surface of the base, and the chip isconnected to the antenna by welding beads.

According to an embodiment of the present invention, the etched surfaceof the chip faces the back of the first surface of the base, the chip isplaced in a slot made through the base, and the chip is connected to theantenna by welding beads, the chip being attached to the base by a dropof resin.

According to an embodiment of the present invention, the etched surfaceof the chip faces the back of the first surface of the base and the chipis connected to the antenna by welding beads located in connection slotsgoing through the base, the chip being attached to the base by a drop ofresin.

According to an embodiment of the present invention, the base is formedof a flexible sheet.

According to an embodiment of the present invention, the surface of thebase which does not receive the double-faced adhesive is provided toreceive the printing of a pattern, of a text or of a code.

The present invention also provides a method of manufacturing anelectronic circuit such as mentioned hereabove, which includes the stepsof: forming a rectangle of double faced adhesive including a slot,gluing the adhesive rectangle on a packaging protective film, ungluingthe adhesive rectangle from the protective film, and assembling it onthe base.

The foregoing objects, features and advantages of the present inventionwill be discussed in detail in the following non-limiting description ofspecific embodiments in connection with the accompanying drawingswherein

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of a label according to a first embodiment ofthe present invention;

FIG. 2 shows a cross-sectional view of the label of FIG. 1;

FIG. 3 shows a top view of a label made according to a second embodimentof the present invention;

FIG. 4 shows a cross-sectional view of the label of FIG. 3;

FIG. 5 shows a top view of a label made according to a third embodimentof the present invention;

FIG. 6 shows a cross-sectional view of the label of FIG. 5;

FIG. 7 shows a top view of a label made according to a fourth embodimentof the present invention;

FIG. 8 shows a cross-sectional view of the label of FIG. 7;

FIG. 9 shows a cross-sectional view of a label made according to a fifthembodiment of the present invention;

FIG. 10 shows a method of manufacturing self-adhesive electronic labelsaccording to an embodiment of the present invention; and

FIG. 11 schematically shows a final packaging of labels according to thepresent invention.

DETAILED DESCRIPTION

The same references designate same elements in the various drawings.FIGS. 1 and 2 show in top view and in cross-section a label 10 accordingto a first embodiment of the present invention. This label includes achip 12 attached by a glue layer 13 on a first surface of a base 14. Anantenna 16 is also attached to the first surface of base 14. Chip 12 iselectronically connected to antenna 16 by connection wires 18. The chipand the wires are caught in a drop of protection resin 19. In thefollowing description, a “double faced adhesive” will designate asegment of a plastic tape conventionally processed to be adhesive on itstwo surfaces, on a strip of solid glue. A first surface of a doublefaced adhesive 20 pierced by a slot 21 is glued on the first surface ofbase 14 to cover the first surface except for the vicinity of resin drop19, located in slot 21. A strippable sheet 24 covers the second surfaceof double-faced adhesive 20.

Chip 12 may be glued to the base by means of a glue, epoxy, or other,and connection wires 18 may be attached by a conventional wiringmachine. Antenna 16 may be formed on the base in a known manner by metaldeposition followed by an etching. The resin drop can be formed bycoating, by casting, or by cloisonné. Base 14 is made of a flexiblematerial of low thickness, for example, a piece of a polyester sheet.

The double faced adhesive is thicker than the resin drop and it formsboth the adhesive portion of the self-adhesive label and the protectivehousing of chip 12. The double-faced adhesive is made in a slightlyresilient flexible material so that the self-adhesive label is adaptedto being glued on a non-planar surface, and is resistant to vibrationsand shocks. The glue coating the double-faced adhesive is a joiner'sglue enabling a lasting and reliable bond. Double faced adhesivescurrently available for sale that may be used, for example, are sold by3M Company under trade name VHB.

As an example, the thickness of base 14 may be 75 μm, the thickness ofantenna 16 may be 17 μm, the thickness of glue 13 may be 20 μm, thethickness of chip 12 may be 180 μm, the thickness of drop 19 may be 300μm, and the thickness of double faced adhesive 20 may be 400 μm. Thus,according to this embodiment, label 10 has a thickness of approximately500 μm. The thickness of double faced adhesive 20 here is much greaterthan the height of drop 19 so that a variation of the height of the dropupon its forming may be tolerated.

FIGS. 3 and 4 show in top view and in cross-section a label 10 accordingto a second embodiment of the present invention. In this embodiment,connection wires 18 and chip 12 are protected by a resin drop 22 formedby filling slot 21 with resin. The forming of drop 22 here is fasterthan according to the previous embodiment. Indeed, the methods offorming drop 19 discussed in relation with FIGS. 1 and 2 are slow,whereas it is here sufficient to fill slot 21 with resin. In thisembodiment, in addition to the previously mentioned functions, slot 21through the double-faced adhesive is used to limit the spreading of theresin, which can be chosen to be very fluid.

FIGS. 5 and 6 show in top view and in cross-section a label 10 accordingto a third embodiment of the present invention. The front surface oretched surface of chip 12, that is, the surface having received thevarious processings intended for the forming of an integrated circuit inplanar technology, is placed against the first surface of support 14according to a so-called flip-chip assembly mode, to be electricallyconnected to antenna 16 via welding beads 26. A resin collar 23 isformed on the circumference of the chip to seal chip 12 on base 14. Thisembodiment requires an assembly by welding beads, which is delicate toimplement, but it enables decreasing the thickness of label 10.

As an example, it is assumed that the welding beads have a substantiallyconstant thickness of 20 μm, and that an allowed variation of 10 μm onlycan be provided for the depth of slot 21. With a thickness of chip 12 of180 μm, a double-faced adhesive of a 210-μm thickness can be used. Ifthe total thickness of base 14 and of antenna 16 is close to 95 μm, alabel 10 with a thickness close to 300 μm only is obtained.

FIGS. 7 and 8 show in top view and in cross-section a label 10 accordingto a fourth embodiment of the present invention. Antenna 16 here islocated on the surface of base 14 which is not covered by double facedadhesive 20. Further, base 14 is crossed by a slot 21 whichsubstantially prolongs slot 21 of double-faced adhesive 20. Chip 12 islocated in slot 21, with its etched surface facing the back of antenna16 and being connected to the back of the antenna by welding beads 26.Slot 21, in base 14 and double faced adhesive 20, is filled with a dropof resin 22. This embodiment requires a slot 21 of the base and aconnection by welding beads, but it enables decreasing the thickness oflabel 10.

As an example, if the thickness of the base is 75 μm, the thickness ofthe antenna is close to 20 μm, the thickness of chip 12 is 180 μm andthe thickness of welding beads 26 is approximately 20 μm, then anadhesive of approximately 135 μm can be used, to obtain a label 10 of athickness close to 230 μm. This thickness is substantially that of aconventional non-electronic self-adhesive label.

FIG. 9 shows in cross-section a label 10 according to a fifth embodimentof the present invention. Antenna 16 is located on the same surface ofbase 14 as in FIGS. 7 and 8. Chip 12 is located in slot 21 of doublefaced adhesive 20, its etched surface facing the back of antenna 16, andbeing connected to the back of the antenna by welding beads 26 throughconnection slots 25 made in base 14.

FIG. 10 illustrates a method of manufacturing self-adhesive labelsaccording to the embodiment described in relation with FIGS. 3 and 4. Aseries of antennas (not shown) has been formed on a mechanically indexedstrip 28 intended for being cut into a series of bases. A chip 12 hasbeen glued at the level of each antenna on the indexed strip, which isprovided to a laminating machine 30. The machine also receives a doublefaced adhesive 20 covered with a protective film 24 on both itssurfaces. A sensor 32 spots the position of each chip 12 and controls apunch 34 to form, in the double faced adhesive, a slot 21 correspondingto this position. Protective film 24 is removed from a first surface ofcut-up double-faced adhesive 20, which is laminated and glued on theindexed strip. Each chip 12 is then connected to the correspondingantenna by connection wires (not shown), after which slot 21 is filledwith drops of resin (not shown). After assembly of the labels, theindexed strip is cut to form the labels, each label is magneticallytested and the functional labels are separated from their protectivefilm to be placed on a packaging strip.

An alternative manufacturing method includes using rectangles of doublefaced adhesive 20 which are precut (separated from one another andcomprising slot 21), for example, by the adhesive manufacturer. Doublefaced adhesive rectangles 20 are then delivered maintained together by astrip of protective film 24, and they are unglued one by one from theprotective film, by a machine or by an operator, to be glued to thebases. The labels can then be manufactured according to the embodimentof FIGS. 1 and 2. In this case, connections 18 and resin drop 19 ofprotection of the chip and connections will be formed before gluing thedouble faced adhesive on base 14. The electromagnetic testing of eachconnected chip 12 may also be performed before gluing the double facedadhesive, which implies that a rejected defective component represents asmaller loss. The labels of FIGS. 3 to 9 may also be formed according tothis alternative.

FIG. 11 shows a packaging strip 36 comprising labels 10, the secondsurface of which has been covered with a logo or a code 38, ready to besold.

Of course, the present invention is likely to have various alterations,modifications, and improvements which will readily occur to thoseskilled in the art. In the embodiment of FIGS. 1 and 2, a cavity may forexample be formed in the upper half of the thickness of base 14 toreceive chip 12, and thus decrease the label thickness and facilitatethe forming of drop 19. Further, the surface of the base which is notglued to the double-faced adhesive may be painted or printed or coveredwith an easily paintable or printable material. Moreover, the precedingdescriptions relate to self-adhesive labels, but the present inventionmay also apply to any self-adhesive electronic circuit, for example, asensor. In this regard, protection resin 22, which is conventionallyopaque, may be replaced in the embodiment of FIGS. 7 and 8 with atransparent protection resin if the chip includes light-sensitivecircuits such as photo-voltaic or charge coupling circuits. Resin drop22 may then be lens-shaped for a better reception of the light by thechip.

Such alterations, modifications, and improvements are intended to bepart of this disclosure, and are intended to be within the spirit andthe scope of the present invention. Accordingly, the foregoingdescription is by way of example only and is not intended to belimiting. The present invention is limited only as defined in thefollowing claims and the equivalents thereto.

1. A self-adhesive electronic circuit including a planar base havingfirst and second base surfaces, an antenna attached on the first surfaceof the base, a chip connected to the antenna, and a double facedadhesive glued on one of the base surfaces, the double faced adhesivehaving an opening and the chip being arranged at least partially in theopening, wherein the double faced adhesive has first and second adhesivesurfaces, wherein the first adhesive surface is glued on one of the basesurfaces, and wherein the second adhesive surface is covered by aprotective cover which is removable to expose the second adhesivesurface as an outward adhesive surface of the self-adhesive electroniccircuit.
 2. The self-adhesive electronic circuit of claim 1, wherein thechip is glued on the first surface of the base and is connected to theantenna by connection wires, the wires and the chip being covered with adrop of resin.
 3. The self-adhesive electronic circuit of claim 1,wherein an etched surface of the chip faces the first surface of thebase, and the chip is connected to the antenna by welding beads.
 4. Theself-adhesive electronic circuit of claim 1, wherein an etched surfaceof the chip faces the back of the first surface of the base, the chip isplaced in a slot made through the base, and the chip is connected to theantenna by welding beads, the chip being attached to the base by a dropof resin.
 5. The self-adhesive electronic circuit of claim 1, wherein anetched surface of the chip faces the back of the first surface of thebase and the chip is connected to the antenna by welding beads locatedin connection slots going through the base, the chip being attached tothe base by a drop of resin.
 6. The self-adhesive electronic circuit ofclaim 1, wherein the base is made of a flexible sheet.
 7. Theself-adhesive electronic circuit of claim 1, wherein the surface of thebase which does not receive the double faced adhesive is provided toreceive printing of a pattern, of a text or of a code.
 8. A method ofmanufacturing the self-adhesive electronic circuit of claim 1, whereinthe attachment of the double faced adhesive on the base includes thesteps of: forming a rectangle of double faced adhesive including anopening, gluing the adhesive rectangle on a packaging protective film,ungluing the adhesive rectangle from the packaging protective film, andassembling the adhesive rectangle on the base.
 9. The electronic circuitof claim 1, wherein the double faced adhesive comprises a double facedadhesive tape.
 10. A method of using the self-adhesive electroniccircuit of claim 1, the method comprising acts of: (A) removing theprotective cover covering the second adhesive surface of the doublefaced adhesive to expose the second adhesive surface as the outwardadhesive surface of the self-adhesive electronic circuit; and (B)adhering the outward adhesive surface of the self-adhesive electroniccircuit to a non-planar surface.
 11. The electronic circuit of claim 1,wherein the protective cover comprises a film.
 12. The self-adhesiveelectronic circuit of claim 1, wherein the chip does not protrude pastthe second adhesive surface of the double faced adhesive.
 13. Anelectronic circuit, comprising: a base having first and second surfaces;an antenna supported by the first surface of the base; a double facedadhesive having first and second surfaces, the first surface of thedouble faced adhesive being adhered to the first surface of the base,the second surface of the double faced adhesive being covered with aprotective cover, the double faced adhesive having a thickness in adirection extending away from the first surface, the double facedadhesive having an opening, wherein at least a portion of the antenna isdisposed in the opening; and an electronic chip disposed at leastpartially in the opening and electrically coupled to the antenna, theelectronic chip having a height in a direction extending away from thefirst surface; wherein the thickness of the double faced adhesive isgreater than or equal to the height of the electronic chip, and whereinthe protective cover covering the second surface of the double facedadhesive is removable to expose the second surface of the double facedadhesive as an outward adhesive surface of the electronic circuit thatenables the electronic circuit to be adhered to a non-planar surface.14. The electronic circuit of claim 13, further comprising connectionwires which electrically couple the electronic chip to the antenna and aresin which covers the connection wires and the electronic chip, theresin having a height in a direction extending away from the firstsurface, wherein the thickness of the double faced adhesive is greaterthan or equal to the height of the resin.
 15. The electronic circuit ofclaim 13, further comprising welding beads which electrically couple theelectronic chip to the antenna, wherein the chip has an etched surfacewhich faces the first surface of the base.
 16. The electronic circuit ofclaim 13, further comprising welding beads which electrically couple theelectronic chip to the antenna and a resin which attaches the electronicchip to the base, the base having a slot in which the electronic chip isarranged, the electronic chip having an etched surface which faces thebase, the resin having a height in a direction extending away from thefirst surface, wherein the thickness of the double faced adhesive isgreater than or equal to the height of the resin.
 17. The electroniccircuit of claim 13, further comprising welding beads which electricallycouple the electronic chip to the antenna and a resin which attaches theelectronic chip to the base, the base having connection slots throughwhich the welding beads reach the antenna, the electronic chip having anetched surface which faces the base, the resin having a height in adirection extending away from the first surface, wherein the thicknessof the double faced adhesive is greater than or equal to the height ofthe resin.
 18. The electronic circuit of claim 13, wherein the base iscomposed of a flexible sheet.
 19. The electronic circuit of claim 13,wherein the surface of the base which does not receive the double facedadhesive is provided to receive printing of a pattern, text or code. 20.The electronic circuit of claim 13, wherein the protective covercomprises a film.
 21. An electronic circuit, comprising: a base havingfirst and second surfaces; an antenna supported by the first surface ofthe base; a double faced adhesive having first and second surfaces, thefirst surface of the double faced adhesive being adhered to the firstsurface of the base, the second surface of the double faced adhesivebeing covered with a protective cover, the double faced adhesive havingan opening, wherein at least a portion of the antenna is disposed in theopening; and an electronic chip disposed at least partially in theopening and electrically coupled to the antenna; wherein the electronicchip is spaced from and does not contact the double faced adhesive, andwherein the protective cover covering the second surface of the doublefaced adhesive is removable to expose the second surface of the doublefaced adhesive as an outward adhesive surface of the electronic circuitthat enables the electronic circuit to be adhered to a non-planarsurface.
 22. The electronic circuit of claim 21, further comprisingconnection wires which electrically couple the electronic chip to theantenna and a resin which covers the connection wires and the electronicchip.
 23. The electronic circuit of claim 21, further comprising weldingbeads which electrically couple the electronic chip to the antenna,wherein the electronic chip has an etched surface which faces the firstsurface of the base.
 24. The electronic circuit of claim 21, furthercomprising welding beads which electrically couple the electronic chipto the antenna and a resin which attaches the electronic chip to thebase, the base having a slot in which the electronic chip is arranged,the electronic chip having an etched surface which faces the base. 25.The electronic circuit of claim 21, further comprising welding beadswhich electrically couple the electronic chip to the antenna and a resinwhich attaches the electronic chip to the base, the base havingconnection slots through which the welding beads reach the antenna, theelectronic chip having an etched surface which faces the base.
 26. Theelectronic circuit of claim 21, wherein the base is composed of aflexible sheet.
 27. The electronic circuit of claim 21, wherein thesurface of the base which does not receive the double faced adhesive isprovided to receive printing of a pattern, text or code.
 28. Theelectronic circuit of claim 21, wherein the protective cover comprises afilm.
 29. The self-adhesive electronic circuit of claim 21, wherein thechip does not protrude past the second adhesive surface of the doublefaced adhesive.